How serious a pull is it? Been riding Harleys sense the 70's and they've all had a pull to the left to some degree. I always figured it was some gyroscopic effect of the flywheels but never new for sure. The rear wheel has to line up with the tranny sprocket so you really can't change alot there but have used the floresent light blubs to align before as well a cool laser level I got awhile back. I would ck the front tire pretty close because it seems to be a variable that hasn't been addressed. I did learn from reading a story about Eric Buell that our exhausts are heavy and hang off the right side causing the left hand drift. That's why he put the exhaust under the middle of his bikes. Smart guy.